Theoretical models study and analysis of the impact of buffer unit in routers for future Internet

In recent years, the router buffer sizing has become one of the hot research topics and researchers have been debating the size of buffers required at core Internet routers. It is very important to size the buffer for routers with very small buffers in future Internet, in particular, in emerging optical networks as optical buffers are needed but very expensive. In the year of 2004, the Stanford research group presented that the core router buffer needs only dozens of packets to meet acceptable link utilization. Then there were a variety of different views presented in the literature. However, all prior studies ignored whether buffer unit is structured in terms of packet or byte. In previous studies, it made no much difference when only TCP traffic was considered. In the year of 2011, our research group studied the buffer sizing in routers with very small buffers when the real-time UDP and TCP traffic coexist. We found that the difference of the buffer unit structure obviously impacts the loss performance of routers with very small buffers. When buffer unit is structured in terms of byte, the UDP packet loss rate is lower than the TCP packet loss rate, when buffer unit is structured in terms of packet, the UDP packet loss rate is higher than the TCP packet loss rate yet. In this paper, we study and analyze this phenomenon. More importantly we present two models independently for the theoretical explanation of this phenomenon.